Companies contemplating the wide spread adoption of Ethernet I/O networks will quickly encounter the problem of how to segment their industrial Ethernet networks. Even for a small manufacturing concern, a facility-wide Ethernet network will be segmented into multiple physical or logical Ethernet network segments. A related problem then becomes how to enable devices on different Ethernet network segments to communicate with each other.
This paper will discuss the preferred network architecture that GM Vehicle Systems intends to pursue for segmenting EtherNet/IP control level and EtherNet/IP device level networks as it begins the process of migrating DeviceNet I/O networks to EtherNet/IP I/O networks. The proposed architecture will route EtherNet/IP implicit message traffic between controllers and the EtherNet/IP capable I/O devices controlled by those controllers. To realize the proposed architecture in a cost effective manner, General Motors will need industrial Ethernet switch suppliers to support a single hop inter-VLAN routing feature.
There is a distinct difference between switching and routing Ethernet traffic. Switching is an ISO/OSI reference model layer 2 activity while routing is an ISO/OSI reference model layer 3 activity. Switching occurs between devices on the same logical network. Routing occurs between devices on different logical networks.
A single hop inter-VLAN routing feature provides line speed routing between devices that would otherwise be using line speed switching, but can’t because the devices belong to different logical Ethernet networks. It is the feature of a true layer 3 switch that remains when you minimize its routing
Paper and presentation from the 2014 ODVA Industry Conference & 16th Annual Meeting
Gary Workman, Manufacturing Engineering Vehicle Systems, General Motors